This invention relates generally to peristaltic pumps and, more particularly, to mechanisms for adjusting the pumping action of peristaltic pumps.
Peristaltic pumps are mechanical devices that pump fluids in a wave-like motion by mechanical compression of a length of flexible tubing. In the medical field, peristaltic pumps are used in such devices as cardipulmonary bypass devices, for pumping blood, and in intraocular lens irrigation and suctioning devices, for pumping irrigation fluids. One particular type of peristaltic pump used frequently in these devices mechanically compresses the length of flexible tubing with a rotating roller head. The roller head has a plurality of rollers positioned about its circumference, which compress the length of flexible tubing against a circular race or channel, moving the fluid in the length of flexible tubing forward in the direction of the rotation of the roller head.
Efficient operation of this type of peristaltic pump requires that the pressure exerted by the roller head against the length of flexible tubing and the circular race be properly adjusted. Too much pressure causes excessive wear and bunching up of the length of flexible tubing, while too little pressure produces inefficient pumping action. A mechanism widely used in the past to adjust this roller head tension is a simple clamp and bolt mechanism. The clamp and bolt mechanism allows the position of either the roller head or the circular race to be adjusted by first loosening the bolts. The roller head or circular race is then rigidly clamped in place by tightening the bolts. Although simple, this mechanism is awkward and difficult to use. Furthermore, this mechanism does not automatically adjust the roller head tension, which is especially important with peristaltic pumps used in medical devices, because the length of flexible tubing must be removed and sterilized after each surgical operation. In addition, this mechanism does not provide a means for continuously adjusting the position of the roller head or the circular race while the pump is in operation, to maintain the proper roller head tension. Accordingly, there has been a need, particularly in the medical field, for an improved mechanism to easily, automatically and continuously adjust the position of the roller head or the circular race to provide the proper roller head tension. The present invention clearly fulfills this need.